用于在前端代码中去除按钮的disabled属性，使其在界面上显示为可点击状态。这仅影响前端表现，不改变后端逻辑(脚本只是辅助，重点是教程)。modifying the front-end code to remove the `disabled` attribute from the purchase button(the script is merely auxiliary; the focus is on the tutorial)